The number of channels available to wireless, local area networks (WLANs) is relatively small. In some instances the number of non-overlapping channels (i.e., separate channels) may be much less than ten. For example, among the seven channels specified by the so-called 802.11b standard and allotted by the Federal Communications Commission (FCC) to WLAN usage, only three are non-overlapping. Because the number of non-overlapping channels is so small, it is very difficult to allocate channels to competing WLANs or to various access points (APs) (e.g., a connecting point between a WLAN cell and a wired infrastructure) within one WLAN.
Complicating matters further, those channels that have been set aside by the FCC, such as the seven channels mentioned above, are currently unregulated. That is, though the FCC has allotted certain channels for WLAN usage, it does not decide who can use these channels, or when they can be used. As a result, nothing prevents a source outside the control of a network administrator (e.g., outside the control of the administrative function or entity of a given WLAN) from interfering with users operating over such channels. Still further complicating matters is the fact that this interference is unpredictable. That is, a given channel may be free of outside interference at one given time, yet may become unavailable due to a high level of interference at another time. Similarly, for a given channel one segment of a network may be free from interference while another segment is virtually unusable at the same time. The unpredictable nature of the interference makes it difficult to efficiently allocate a given channel to a network at any given period of time.
Another challenge related to the allocation of channels to WLANs is the fact that WLANs cannot make use of existing, so-called hexagonal layouts used by cellular networks. This is because a signal propagated by a WLAN usually travels entirely indoors compared to a cellular network, where signals travel mostly outdoors. Said another way, because a WLAN generated signal travels mostly indoors, the shape of the cells (i.e., coverage areas associated with each AP) is greatly affected by the internal structure of the building, etc. within which the WLAN is located.
Because of the high level of interference involved in WLANs, and the unavailability of hexagonal designs, a new framework for allocating channels to WLANs is needed.